Alleged Gambino crime family boss John “Jackie the Nose” D’Amico was released from the jail three months ago after conspiracy charges against him were dropped.

Last night a prison source said: “There are at least four other accused Mafia mobsters still there, among some of the most wanted criminals on the planet.

“It is not a place for the faint-hearted.”

Hamza, who lost both hands and an eye in an explosion in Afghanistan, had begged to remain in Britain on medical grounds and also expressed fears he would be tortured by US authorities.

He was finally extradited after an eight-year court battle that cost taxpayers £2.7million in legal fees, benefits and prison costs.

He left Britain on Friday on a US military plane escorted by armed federal marshals.

Also on board the five-hour flight from RAF Mildenhall in Suffolk were fellow suspects al Fawwaz and Abdul Bary, both wanted in America over alleged roles in the bombings of two US embassies.

All three are being kept in isolation units at MCC New York.

Authorities in the US were jubilant at the men’s extradition despite reports it could still take three years for Hamza to face trial.

If convicted, the cleric is expected to be held in an impregnable “supermax” jail.

But last night he defiantly vowed to continue fighting for his extremist beliefs.

In a posting on a radical website he said: “Jazakallah khair (All thanks to God Almighty) for ur duas (prayers) and support, this is what Allah has promised us and I have chosen this path.

“The fight between good and evil will continue for as long as I am alive.

“Muslims will remember me in their dua and Allah will not let them down.”

Last night campaigners called for the men to be repatriated to Britain if convicted.

Asim Qureshi, of London-based Cageprisoners, said: “We would want to see them, if convicted, serving any sentence in the UK, ­particularly when you consider the kind of treatment detainees face in US prisons.”

Two other extradited men, Syed Talha Ahsan, 33, and ­Babar Ahmad, 38, pleaded not guilty to terrorism charges at a court in New Haven, ­Connecticut.

Authorities say they were charged in Connecticut ­because an internet service provider there was used to run websites that sought to raise cash and recruit ­fighters for terrorist groups.